Difficulties have been experienced in incinerator design in achieving complete combustion of the waste material. In order to increase the efficiency of the combustion and reduce the discharge of pollutants into the atomsphere, the incinerator often includes a secondary zone of combustion and air is delivered to the secondary combustion chamber to burn any combustible residue in the waste gases.
Recently, through the increased use of plastic materials, it has been found that the conventional incinerator system is not totally effective in preventing the discharge of gaseous pollutants to the atmosphere. This is due to the greater BTU content of the plastic material and the higher temperatures involved in the combustion.
When a charge of highly flammable material, such as plastic, is fed to the incinerator, there may be insufficient air to completely burn the charge with a result that a short surge of smoke may be emitted from the incinerator. To eliminate this problem many municipalities require a secondary combustion chamber which is connected to the stack and air is supplied to the secondary combustion chamber to completely combust any residual combustible material in the waste gases. The conventional secondary combustion chamber normally includes a refractory lined chamber along with baffling to slow the flow of waste gases through the chamber. However, due to the intense heat that is involved in the secondary combustion chamber maintenance and repair of the chamber is commonly required.